OnStar Button Malfunction

OnStar Button Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information






Circuit/System Description

The OnStar(R) button assembly consists of 3 buttons, Call/Answer, OnStar(R) Call Center, and OnStar(R) Emergency. The telematics communication interface control module supplies the OnStar(R) button assembly with 10 V via the keypad supply voltage circuit. Each of the buttons, when pressed, completes the circuit across a resistor allowing a specific voltage to be returned to the telematics communication interface control module over the keypad signal circuit. Depending upon the voltage range returned, the telematics communication interface control module is able to identify which button has been activated.

Reference Information
Schematic Reference

OnStar Schematics OnStar Schematics
Connector End View Reference

Component Connector End Views Hybrid/EV Battery Pack X1
Electrical Information Reference

* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Programming and Relearning for scan tool information

Circuit/System Verification

Note: Contact the OnStar(R) Call Center first before pressing the emergency button in order to notify them of the test.

Vehicle in Service Mode, press the OnStar(R) Call buttons one at the time. Verify that all of the OnStar(R) buttons operate normally.

If some OnStar(R) buttons are inoperative but not all, replace the OnStar(R) button assembly.
If none of the OnStar(R) buttons operate, refer to circuit/system testing.

Circuit/System Testing

1. Vehicle OFF, disconnect the harness connector at the S51 telematics button assembly.
2. Test for less than 10 Ohms between the button assembly ground circuit terminal E and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Vehicle in Service Mode, test for less than 1 V between the keypad signal circuit terminal B and ground.

• If greater than the specified range, test the keypad signal circuit for a short to voltage. If the circuit tests normal, replace the K73 telematics communication interface control module.

4. Vehicle OFF, test for 0.800 kOhms -1.0 kOhms between the keypad signal circuit terminal B and ground.

• If less than the specified range, test the keypad signal circuit for a short to ground. If the circuit tests normal, replace the K73 telematics communication interface control module.
• If greater than the specified range, test the keypad signal circuit for an open/high resistance. If the circuit tests normal, replace the K73 telematics communication interface control module.

5. Vehicle in Service Mode, test for 9.5-10.5 V between the keypad supply voltage circuit terminal A and ground.

• If less than the specified range, test the supply voltage circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K73 telematics communication interface control module.
• If greater than the specified range, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the K73 telematics communication interface control module.

6. If all circuits test normal, test or replace the S51 telematics button assembly.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Communication Center Call Switch Replacement Service and Repair
* Control Module References Programming and Relearning for CIM replacement, programming and setup